PROJECT SUMMARY/ABSTRACT My career goals are to become a physician-scientist focused on translating novel laboratory discoveries into safe and efficacious therapies for children with high-risk pediatric solid tumors. This proposal describes a 5- year plan designed to facilitate my development into an independent translational physician-scientist through the acquisition of critical technical skills, integrated with didactic training and comprehensive mentoring from a diverse team of tenured faculty members at the University of Pennsylvania (Penn) and the Children?s Hospital of Philadelphia (CHOP). I will conduct the proposed studies under the outstanding and proven mentorship of Dr. John Maris, an international leader in translational neuroblastoma research. Additionally, my dedicated Advisory Committee is comprised of highly regarded physician-scientists with diverse expertise in cancer biology and immunotherapy. Finally, the scientifically collaborative, resource-rich research environment at Penn and CHOP provides an ideal setting to conduct these translational studies. The proposed research focuses on the signaling co-receptor glypican-2 (GPC2). Our laboratory has discovered that GPC2 is glycophosphatidylinositol (GPI)-linked to the extracellular surface of neuroblastomas, but is not found on a majority of normal pediatric tissues. I have also found that neuroblastomas are dependent on GPC2 for tumor growth. To capitalize on GPC2?s differential expression, I have performed proof-of-concept in vivo efficacy studies in neuroblastoma patient-derived xenograft (PDX) murine models showing that a GPC2-targeted antibody drug conjugate (ADC; D3-GPC2-PBD) results in sustained tumor regression. The malignant mechanisms and the ability to selectively target other glypicans, such as GPC3, with immune-based therapies have been well-studied. However, GPC2?s role in promoting tumorigenesis, the suitability of GPC2 as a safe and effective target for immunotherapeutics, and the optimal immune-based therapy approach to target GPC2, all currently remain undefined. I hypothesize that GPC2 is a critical regulator of oncogenic signaling pathways in neuroblastoma and, given its robust differential expression, is an ideal cell surface molecule for immune-based therapeutic approaches. Thus, I propose to (1) Define the mechanisms underlying aberrant GPC2 cell surface expression and oncogenicity in neuroblastoma, (2) Determine the efficacy and safety profile of the D3-GPC2-PBD ADC in neuroblastoma, and (3) Engineer GPC2-redirected chimeric antigen receptor (CAR) T cells and establish their efficacy in neuroblastoma. In summary, I will take advantage of the intellectual strength and track-record of my mentor and Advisory Committee, as well as the expertise, laboratory facilities, and scientific resources available at CHOP and Penn to successfully accomplish this proposed research and career development plan. These efforts will provide an outstanding foundation for my career as a physician-scientist and the development of an independent translational research program.